Medical Rubber Composition Gas Permeability
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Solution Overview
Problem
Medical rubber parts, such as nozzle caps for prefilled syringes, face challenges in achieving optimal gas permeability while maintaining non-oozing characteristics and moldability, leading to issues with sterilization efficiency and productivity.
Innovation Solution
A medical rubber composition comprising isobutylene-isoprene rubber, diene-based rubber, and silica with a BET specific surface area not lower than 130 m2/g, where the isobutylene-isoprene rubber constitutes 30-55 parts by mass, along with a peroxide-based crosslinking agent and triazine derivative, enhances gas permeability and moldability, ensuring effective sterilization and reduced residue removal time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional rubber compositions are used to maintain non-oozing characteristics and moldability, then structural integrity is preserved, but gas permeability is insufficient for efficient sterilization
Solution Approach 1:
The patent changes the chemical composition parameters of the rubber by incorporating specific ratios of halogenated isobutylene-isoprene rubber (5-25 parts), diene-based rubber (75-95 parts), and silica filler (2-10 parts), along with specific crosslinking agents. This parameter optimization achieves both non-oozing characteristics and enhanced gas permeability for efficient sterilization.
Solution Approach 2:
The patent creates a composite rubber material by blending halogenated isobutylene-isoprene rubber with diene-based rubber and incorporating silica filler. This composite structure combines the chemical resistance and non-oozing properties of halogenated rubber with the gas permeability and processability of diene-based rubber, resolving the contradiction between reliability and productivity.
2Productivity
If rubber composition is optimized for gas permeability, then sterilization efficiency improves, but non-oozing characteristics and moldability deteriorate
Solution Approach 1:
The patent optimizes the composition parameters within specific ranges: halogenated isobutylene-isoprene rubber at 5-25 parts, diene-based rubber at 75-95 parts, and silica at 2-10 parts. These controlled parameter changes ensure sufficient gas permeability for sterilization while maintaining the non-oozing characteristics and moldability required for manufacturing.
Solution Approach 2:
The patent incorporates silica filler (2-10 parts per 100 parts of rubber) to create a controlled porous structure that enhances gas permeability for sterilization efficiency while the crosslinking system maintains structural integrity to prevent oozing and ensure proper moldability.
3Reliability
If ethylene oxide gas sterilization is performed, then sterility is achieved, but residues require extended removal time
Solution Approach 1:
The patent modifies the rubber's physical and chemical parameters through composition optimization and crosslinking, which enhances gas permeability. This allows ethylene oxide gas to penetrate and deaerate the rubber matrix more quickly after sterilization, reducing the time required to remove residues such as ethylene glycol and ethylene chlorohydrin.
Solution Approach 2:
The patent enables continuous gas exchange through the rubber material by optimizing its permeability characteristics. The crosslinked network structure maintains open pathways that allow continuous deaeration of sterilization residues, preventing accumulation and reducing the overall time required for complete residue removal.
4Reliability
If vapor sterilization is performed, then sterility is achieved, but adsorbed water requires extended drying time
Solution Approach 1:
The patent optimizes the rubber composition and crosslinking density to create a structure with controlled porosity and enhanced gas permeability. This allows rapid evaporation and removal of adsorbed water molecules after vapor sterilization, significantly reducing the drying time required to achieve complete sterility without moisture retention.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composition achieves improved gas permeability for swift sterilization and residue removal, maintaining non-oozing characteristics and high moldability, thereby enhancing the productivity of prefilled syringes and preventing nozzle cap loosening during deaeration.
Implementation Method 1
a silica having a BET specific surface area not lower than 130 m2/g... enhances gas permeability
Data Source
AI summary
A medical rubber composition can contain, comprise, consist, or consist essentially of: (a) an isobutylene-isoprene rubber: (b) a diene-based rubber; and a silica having a BET specific surface area not lower than 130 m2/g. An amount of (a) the isobutylene-isoprene rubber contained in 100 parts by mass of a rubber component composed of (a) the isobutylene-isoprene rubber and (b) the diene-based rubber can be larger than 30 parts by mass and smaller than 55 parts by mass.